Health officials say the state of Arizona should be preparing for a major spike in flu cases.
The Centers for Disease Control says the flu is currently widespread in 21 states and the hardest hit are Arizona, California and Nevada.
While flu season is technically from early October to January, the Arizona Department of Health and Human Services says is has seen an increase in the number of cases confirmed in late January and early February.
Even in a year of moderate flu activity, tens of thousands of Americans could die. In Arizona, more than 4,000 people are hospitalized because of complications each year and up to 700 die.
Officials say the influenza virus is very contagious and the best way to prevent the illness is by receiving an annual vaccine.